Weaving looms with a fluidic weft thread insertion for producing a fabric having a predetermined fabric pattern are operated in combination with a jacquard which controls the repeated shed formation of the warp threads. One weaving cycle includes an opening of a warp shed, an insertion of a weft thread into the warp shed and closing of the warp shed followed by a beat-up of the inserted weft by a reed against the fabric. A fluidic weft insertion by one or more nozzles such as air jet nozzles requires a special attention to the shed formation to avoid damaging the warp threads by the jets and to optimally control the shed formation along the weaving width defined between a weft entrance and a weft exit of the warp shed.
A jacquard of modern construction comprises a plurality of electrically or electronically controllable warp lifting and lowering components or drives which, for example, are driven by controllable electric motors. Such jacquards do not comprise any knives nor any drives for such knives.
Each warp thread of all warp threads in the loom is guided and driven by the jacquard operating components including harness cords, etc., which lift and lower the respective warp thread through coupling elements which connect the harness cords with respective drives and with heddles and pull back members to move each of the warp threads. Each harness cord and its pull back member are guided and driven by a respective individual operating component or drive motor in such a way that the warp shed is formed by the warp threads. For this purpose one group of warp threads is moved vertically from a first upper position to a second lower position while another group of warp threads is simultaneously vertically moved from the second lower position to the first upper position to thereby form the warp or loom shed. An electronic control or CPU is provided for the controlled motion of the warp threads for the shed formation and respective shed closure. The electronic control drives each of the warp operating components such as electric motors in accordance with a preselected program by transmitting signals from the control unit, for example, to the above mentioned individual electric motors for driving or moving the warp threads for the proper shed formation also referred to as shedding.
European Patent Publication EP 0,353,005 B2 (Palmer) discloses an example of a weaving loom with a drive mechanism that performs the function of a jacquard as described above. Each individual warp thread is moved by its heddle and a respective heddle actuator between end positions which are variable in accordance with a fabric pattern representing program stored in the memory of a computer. The operation is such that a preselected pattern is formed in the textile being woven. The control data stored in the computer memory represent selected operating parameters that result in an “oblique or parabolic shedding” during the weaving operation.
The disclosure of the European Patent Publication EP 0,353,005 B2 does not provide for different shed formation configurations for different types of looms such as mechanical looms with a weft insertion by two rapiers or fluid jet looms with a fluidic weft insertion by fluid nozzles for transporting a weft thread through the warp or loom shed having an entrance and an exit. Thus, the shedding or the shed motion profiles for the same fabric pattern are identical, namely oblique or parabolic for a loom with mechanical weft insertion and for a loom with pneumatic weft insertion. The use of either oblique or parabolic shedding in any type of loom does not take into account that different types of looms have different shedding requirements for achieving an optimal weaving operation.